1. Field of the Invention
The present invention relates to a method and an apparatus for performing a noncontact measurement of a dielectric constant of a dielectric film on a substrate.
2. Description of the Background Art
Conventionally, an oxide film (SiO2) which is a dielectric thin film (hereinafter, referred to as “dielectric film”) is formed on a semiconductor substrate (hereinafter, referred to as “substrate”), and the oxide film is used as an interlayer insulating film in an integrated circuit. With high integration of an LSI, recently, the problem of signal delay due to the characteristic of the dielectric film has become appreciable. In order to suppress the signal delay, a low dielectric-constant interlayer insulating film (hereinafter, referred to as “low dielectric constant film”) is needed and various kinds of low dielectric constant films termed “low-k film” have been developed.
The low dielectric constant film has problems of unstable film quality, low resistance against etching gases and low mechanical strength, and the like, as compared with the conventional oxide film. Therefore, it is difficult to measure the dielectric constant of a low dielectric constant film by bringing a probe into contact therewith immediately after formation of the low dielectric constant film. In order to measure the dielectric constant of the low dielectric constant film, it is necessary to provide electrodes in the final step of an LSI manufacturing process and thereafter apply a voltage between the electrodes for the measurement.
In order to improve manufacturing yield of the LSI, however, it is preferable to measure and control the dielectric constant of the low dielectric constant film immediately after film formation, instead of measuring the dielectric constant after the final step in the manufacturing process.